Electrification of small fleets has ceased to be the lot of experimenters and has become the standard for thousands of fishermen and tourists. Battery outboard motor It's not just an alternative to gasoline engines, but often the only solution for quiet and eco-friendly fishing, because the lack of vibration, exhaust gases and characteristic noise allows you to sneak up on fish at a minimum distance, which is highly appreciated by athletes.
However, to make the system work reliably, it is not enough to simply buy the first battery you find. Traction batteries They are very different from the starter car, which is designed for short-term high-current returns. Incorrect selection of components can lead to rapid degradation of the energy source or failure of the energy source. electric motor.
In this article, we will discuss all the nuances of creating an autonomous power system, you will learn how to calculate the operating time, why. The discharge depth should not exceed 80% for lithium batteries. What connectivity schemes will ensure maximum efficiency.
Principal differences of traction batteries from starter
Many beginners make the mistake of trying to feed battery-poweredStarter batteries (SLIs – Starting, Lighting, Ignition) are designed to give off a tremendous current in a fraction of a second, and then recover instantly from the generator. Their internal structure of the plates is thin and porous, which provides a large contact area, but makes them vulnerable to deep discharge.
Unlike them, traction Deep Cycles are designed to last long periods of medium-sized discharge, can give off energy for hours while maintaining a stable voltage, and are structurally thicker, allowing them to withstand hundreds of charge-discharge cycles without destroying the active mass, and using a starter battery as a traction battery will cause it to fail after 10 to 20 cycles.
The modern market offers several chemical formulations, each with its own specifications of operation, depending on the budget, storage conditions and weight requirements of the equipment.
- 🔋 AGM and GEL (Lead Acid): Sealed, maintenance-free, safe to transport, but have a high weight and limited cycle life.
- ⚡ LiFePO4 (Lithium-Iron-Phosphate): Lighter than lead 3-4 times, have built-in BMS, withstand thousands of cycles, but require a special charger.
- 💧 Liquid electrolyte (WET): Cheap, but require constant water level monitoring, vertical storage and good ventilation due to the release of gases.
⚠️ Attention: Never use car starter batteries for long-term operation of the electric motor. Deep discharge below 50% irreversibly sulfates the plates, turning the battery into useless cargo.
Why is lithium more expensive, but more profitable?
LiFePO4 batteries have a cost of ownership below lead in terms of 5 years of operation. Despite the high initial price, they withstand 2000-5000 cycles against 300-500 for AGM, and their weight makes it easy to carry the tackle to one person.
Calculation of capacity and time of autonomous operation
Reserve planning is a critical stage in preparing for the water to figure out how long it takes you to get out. battery-powered It can run on a single charge, you need to know the current you're using and the battery capacity. The basic formula is simple: the capacity (Ah) is divided by the current (A), but in reality, it's more complicated because of the Peckert effect and the voltage drop.
Electric motors use different currents depending on the speed of the rotor. At maximum speeds, consumption can be 3-4 times higher than at minimum speeds. So you always need to keep the calculations in reserve. For lead batteries, the usable capacity is only 50-60% of the nominal value, whereas for LiFePO4 this parameter reaches 90-95%.
Consider the approximate autonomy metrics for common equipment combinations, and the data are for medium speed mode, which is most relevant for trolling.
| Motor type (Traction) | Capacity of AKB (Ach) | Chemistry | Approximate working hours |
|---|---|---|---|
| 30 lbs (12V) | 100 AH | AGM/GEL | 3.5 - 4 hours |
| 55 lbs (12V) | 100 AH | AGM/GEL | 2 - 2.5 hours |
| 30 lbs (12V) | 100 AH | LiFePO4 | 6 - 7 hours |
| 80 lbs (24V) | 100 Ah (2 units) | LiFePO4 | 3.5 hours |
It is important to consider that cold water and wind significantly increase the resistance to the boat, which causes the motor to consume more energy to maintain speed. Always lay a capacity reserve of 20-30% for contingencies.
For lead batteries, use only 50% capacity, for lithium - up to 90%, this rule will extend the life of the battery many times over.
Connection schemes and parallel operation of batteries
Powerful electric motors often require 24 or 36 volts, whereas a standard battery produces 12 volts. In such cases, a serial connection is used. If you want to increase the running time while maintaining the voltage of 12 volts, the batteries are connected in parallel. Switching errors can lead to short circuits or equipment failure.
In a series of connections (+ first-to- - second, the voltages are added and the capacitance remains unchanged.+ ce +, - ce -It is essential to use batteries of the same model, age and wear, especially when connected in parallel.
- 🔌 Cables: Use copper wires with a cross section of at least 16 mm2 (6 AWG) for currents up to 50A and 25 mm2 (4 AWG) for currents above 50A.
- 🛡️ Defense: Be sure to install a fuse or an automatic switch on the plus wire in the immediate vicinity of the battery terminal.
- 🔗 Balancing: When connecting lithium batteries in series, use models with balancing function or external balancers.
Use special terminals and tips, squeezed by a hydraulic press, to connect, twisting or soldering in high-current load areas is unacceptable, as they create additional resistance and a heating point.
⚠️ Attention: When you're in parallel, try to make wires of the same length, and different wire lengths will cause uneven current and discharge one battery faster than the other.
☑️ Checking before getting on the water
Charger selection and maintenance
The quality of the charge directly affects the battery life. Battery outboard motor It's going to be fun for years only when you use a smart charger (CD) with a multi-stage algorithm. Cheap transformer RAMs often recharge the battery, causing the electrolyte to boil and corrosion of the plates.
Modern chargers have desulphation, volumetric charge (Bulk), absorption (Absorption) and maintenance (Float). For lithium batteries, it is critical to have a LiFePO4 profile that turns off the charge when the upper cell voltage threshold (usually 3.65V) is reached.
Regular maintenance includes visual inspection of the housing for bloating, electrolyte density check (for models to be served) and cleaning of the terminals from oxides with soda solution. It is better to store the batteries in a charged state at a temperature of about +15 ° C.
If you leave the boat for the winter, fully charge the battery and turn off the sub- terminal. Every 2-3 months, check the voltage and recharge if necessary.
Common errors in the system assembly
When building your own power system, enthusiasts often neglect basic electrical safety rules, and one of the biggest mistakes is using thin wires that heat up under load, losing up to 15-20% of energy as heat, which not only reduces efficiency, but also creates a risk of fire.
Another problem is the savings on switching: using low-quality car crocodiles or twists instead of reliable terminals leads to a drop in voltage at the contacts, the engine may not reach full power, and there will be sparking at the place of poor contact.
The ventilation of the battery compartment is also often ignored. Although modern AGM and GEL batteries are sealed, when overcharging or malfunctioning, they can release gases through the valves.
- ❌ No safety lock: A short circuit can cause wires to melt and fire in seconds.
- ❌ Other batteries: Installing a new battery in a pair to an old one will result in the quick death of both.
- ❌ Unsealed boxing: Getting water on the terminals will cause corrosion and self-discharge.
Outlook and outcome recommendations
Use of use battery-powered Technology is constantly improving, making batteries lighter, more capacious and more affordable, and moving to electric power requires initial investment and knowledge, but in return, it gives you freedom from the smell of gasoline, noise and vibration.
With the right components and compliance with the rules of operation, such a system lasts for years without the need for complex maintenance, the main thing is to respect the physics of the processes and not save on safety.
Can lithium be charged in the cold?
Charging LiFePO4 at temperatures below 0°C results in irreversible lithium metallic coating of the anode and loss of capacity. Charge only at plus temperature.
Can I use a conventional car battery for an electric motor?
You can technically start the motor, but you can't do it regularly. A car battery (SLI) is not designed to be deep discharged. After 10-15 discharge cycles, up to 50% of it will drop critically and it will stop holding charge. Electric motors only need traction batteries (Deep Cycle).
How long does a 100-Ah traction battery charge?
The charger's lead battery, 100 Ah 10A (10% of capacity), is charged for about 12-14 hours, the lithium battery will be charged in 8-10 hours and the high-power charger (20A) will be charged in just 4-5 hours.
Which is better: one battery or two smaller batteries?
For 12-volt systems, one high-quality battery is better, to avoid problems with uneven discharge when connected in parallel. For 24/36-volt motors, you have to use several batteries in series, and then their parameters should be perfectly identical.
Do I need to completely drain the battery before charging?
No, it's a myth left over from the days of nickel-cadmium batteries: Lithium and modern lead (AGM/GEL) batteries are better stored and charged without going to full zero. Deep discharge is bad for any chemistry.